In response to the need for detecting column concentrations of greenhouse gases in the marine atmosphere,a 1.57 µm near-infrared laser heterodyne radiometric detection system suitable for shipborne platforms was developed.An image tracking algorithm was developed based on a low-cost surveillance pan-tilt system.The algorithm delay was reduced by simplifying the image processing and control algo-rithms.This enabled stable solar tracking on a shipborne dynamic platform.A measurement method with local oscillator laser temperature step tuning was proposed.This reduces the impact of tracking errors and non-short noise,thereby improving the signal-to-noise ratio of the measurements.Sea trials were conduct-ed in the South China Sea using the system,and the maximum measured tracking error was 1.98 mrad,meeting the requirements for laser heterodyne detection.Continuous monitoring of atmospheric CO2 col-umn concentration was achieved during both cruising and drifting modes.The fluctuation in the measured CO2 column concentration was less than±1.0×10-6,reducing the fluctuation range to 1/12 of that ob-served with traditional local oscillator laser current tuning.This system provides the technical means for subsequent detection of background greenhouse gas column concentrations in the marine atmosphere.
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